Pressure sensor and temperature sensor

Abstract

A force sensor comprises a substrate having a movable unit which is displaceable in response to one of an applied force and acceleration; an electron emission unit having a cathode for emitting electrons in accordance with an applied potential; an electron absorption unit having an anode for capturing electrons emitted from the cathode, the electron emission unit and the electron absorption unit being formed on a surface of the substrate; and a control unit for, on the basis of the displacement of the movable unit, controlling the electron capturing efficiency of the anode with respect to electrons emitted from the cathode.

What is claimed is: 
     
       1. A pressure sensor comprising: a substrate having a movable unit which is displaceable in response to an applied force;   an electron emission unit having a cathode for emitting electrons in accordance with an applied potential;   an electron absorption unit having an anode for capturing electrons emitted from said cathode, said electron emission unit and said electron absorption unit being formed on a surface of said substrate;   said movable unit comprising a diaphragm formed by thinning said substrate at a location between said electron emission unit and said electron absorption unit, the diaphragm being deformable by pressure in an introduction port opening to the diaphragm;   said diaphragm functioning as a control means for controlling the electron capturing efficiency of said anode with respect to electrons emitted from said cathode, and being displacable to block an electron path from said cathode to said anode, thereby controlling said electron capturing efficiency.   
     
     
       2. A pressure sensor according to claim 1, further comprising an electric field defining electrode for defining the electric field distribution in the vicinity of said anode. 
     
     
       3. A pressure detection type temperature sensor comprising: a substrate having a movable unit which is displaceable in response to an applied force;   an electron emission unit having a cathode for emitting electrons in accordance with an applied potential;   an electron absorption unit having an anode for capturing electrons emitted from said cathode, said electron emission unit and said electron absorption unit being formed on a surface of said substrate;   said movable unit comprising a diaphragm formed by thinning said substrate at a location between said electron emission unit and said electron absorption unit, a gas filled unit on the back side of said movable unit, the gas filled unit functioning as a temperature-pressure conversion means for applying a volume change of said gas due to a temperature change as a pressure change to deform the diaphragm;   said diaphragm functioning as a control means for controlling the electron capturing efficiency of said anode with respect to electrons emitted from said cathode, and being displacable to block an electron path from said cathode to said anode, thereby controlling said electron capturing efficiency.   
     
     
       4. A combined pressure and temperature sensor device comprising: a substrate having first and second movable units, each being displaceable in response to an applied force;   an electron emission unit for each of said movable units and having a cathode for emitting electrons in accordance with an applied potential;   an electron absorption unit for each of said movable units and having an anode for capturing electrons emitted from said cathode, said electron emission unit and said electron absorption unit being formed on a surface of said substrate;   said first movable unit comprising a first diaphragm formed by thinning said substrate at a location between said electron emission unit and said electron absorption unit, the first diaphragm being deformable by pressure in an introduction port opening to the diaphragm;   said second movable unit comprising a second diaphragm formed by thinning said substrate at a location between said electron emission unit and said electron absorption unit, a gas filled unit on the back side of said movable unit, the gas filled unit functioning as a temperature-pressure conversion means for applying a volume change of said gas due to a temperature change as a pressure change to deform the second diaphragm;   said first and second diaphragms functioning as control means for controlling the .electron capturing efficiency of said anode with respect to electrons emitted from said cathode, and being displacable to block an electron path from said cathode to said anode, thereby controlling said electron capturing efficiency.   
     
     
       5. A temperature/force sensor device according to claim 4, wherein the cathode of said pressure sensor and the cathode of said temperature sensor are commonly used in said pressure sensor and said temperature sensor. 
     
     
       6. A temperature/force sensor device according to claim 3, wherein said gas in said gas filled unit is an inert gas.